Now a new report casts some doubts about the future of Google+. According to The Wall Street Journal, comScore claims that while tens of millions of users are signing up, they are not doing much once they are there. comScore's numbers show that between September 2011 and January 2012, Google+ users only spend three minutes a month on the service.

Those numbers are dwarfed by those of Facebook, who has 845 million users. comScore claims that during the same time period, Facebook users spent a whopping six to seven hours a month on the service. comScore's numbers are for PC access and don't count mobile users.

Other companies report slow response to Google+ compared to Facebook. Zynga, which launched games on Google+ several months ago, has not seen as much activity as planned. Its COO John Schappert said, "So far, Google+ is a nice platform but it's been slow on the uptick with users right now."

Intel says that while its Google+ page gets dozens of comments to its posts on that service, its Facebook page gets thousands, thanks it part to its nine million "fans".

Google is trying to defend itself, with a spokesperson saying that comScore's numbers are "dramatically lower" than Google's own internal numbers. However, the company declined to offer up its own user statistics.